In my experience, bio-based oil well cement retarders do not provide the consistency needed to control thickening time accurately. (This is at least, the case among types of cement used in oil wells). The main reason is that the production of natural organic retarders varies from lot to lot and batch to batch.
The problem with organic retarders
Down-hole conditions, process control and small variations in cement quality; all play a significant part in the inconsistencies of natural organic retarders and other biopolymers used in the industry. Those such as the cellulose derivative, hydroxyethylcellulose, used as a common fluid loss additive in oil well cementing, experience the same pitfalls as other biopolymers within the oil and gas industry.
We can take a look at an organic molecule and a synthetic polymer. These are both used to control thickening time of the cement slurry. We can easily see why it is the much safer and best choice to opt for a synthetic product.
Thickening time, however, also depends on the:
- Job conditions
- The validity of the BHST
- The determination of the BHCT
- The mix water preparation
- Density control
- Plus other operational aspects.
This analysis is the role of the service company. If we take aside the necessary design and operational controls, it is clear that the first step to making consistent and predictable cement slurry is to treat it with synthetic additives.
Encouraging results from a synthetic retarder trial
Recently, I came across a system that claims to provide excellent results. Even more importantly, reproducibility in thickening within a very, very low standard deviation. This is an excellent advantage to lower costs, laboratory time (e.g., equipment usage) and increases the service quality we deliver to our costumers. Well control, zonal isolation and well integrity are all positivity affected. This maximizes well security and operational safety.
This synthetic retarder provides reproducible results, increases safety through additive engineering. This, in turn, offers predictable results based on the system’s designed linearity.
The system offers excellent fluid loss data, thickening time results, rheology, strength retrogression, expandability. It is cost effective and rigid. It has thermal stability and can perform in HPHT conditions (temperatures as high as 450 F), as well as in temperatures as low as 100 F. The linear response makes this state of the art and a safe-to-use oil well cement system.
After probably only a few years in the industry, we all know well that biopolymer-based systems commonly used have entirely too much variance and other side effects. Sure, they work, but there is no real predictability. That can be very difficult for our laboratory guys with obvious implications in service quality.
Here I will introduce a simple truth, we all know:
The more time the slurry spends in the lab, the higher the risk for the well
Risk elevation can be dangerous and costly to operators.
We derive biopolymers in a naturally organic way, and their quality may vary significantly from lot to lot. Variation in quality makes inventory control more difficult for services companies. This is in addition to the issues already mentioned, all with tremendous effect on service quality.
On the contrary, synthetic cement retarders will provide accuracy time after time. This synthetic product, like any other, is man-made, so the reaction environment is controlled, and it does not change. It’s purely linear, so if you want 2hrs, you can treat with 0.02gal/sks. If you want 3 hrs, you can treat with 0.03gal/sks, for instance.
For inquiries about these cement retarders, and how you can obtain samples and brochures, send email to email@example.com